Switch of the screw selector type



-J. BAUDET SWITCH oF THE SCREW SELECTOR TYPE Aug. 27, 1963 Filed Dec. 19. 1961 '7 Sheets-Sheet 1 Fieri.

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Aug. 27, 1963 l ,1. BAUDET 3,102,114

l SWITCH OF THE SCREW SELECTOR TYPE Filed Dec. 19, 1961 'T Sheets-Sheet 2 frief.

Aug. 27, 1963 J. BAUDET 3,102,174'

SWITCH oF THE SCREW SELECTOR TYPE Filed Dec. 19. 1961 '7 sheets-sheet s Aug. 27, 1963 J. BAUDET swIToH oF THE scREw SELECTOR TYPE '7 Sheets-Sheet 4 Filed Dec. 19. 1961 Aug. 27, 1963 J. BAUDET swITcH oF THE scREw SELECTOR TYPE Filed Dec. 19, 1961 '7 Sheets-Sheet 5 Aug. 27, 1963 J. BAUDET y 3,102,174 v` SWITCH .oF THE SCREW SELECTOR TYPE Filed Dec. 19. 19561' '1 sheets-sheet e f' Aug. 2',A 1963 J, BAUDET SWITCH oF frm: scREw SELECTOR TYPE '7 Sheets-Sheet 7 Filed Deo. 19. 1961 .SMM

United-States Patent 3,102,174 SWITCH F THE SCREW SELECTR TYPE Jacques Baudet, Suresnes, Seine, France, assignor to La Telemecanique Electrique, Nanterre, France, a jointstock company of'France Filed Dec. 19, 1961, Ser. No. 160,471

Claims priority, application France Dec. 23, 1960 9 Claims. (Cl. 20D-33) The present invention relates to :an 4electric switch for operating or controlling 'an industrial apparatus such as a lifting device or the like, having an alternating movement, as for example a hydraulic pressure accumulator.

In this type of apparatus, contacts must -be operated as a function of the real position of the member in oper-ation.

This type of switch usually comprises one or more arms mounted on a shaft, which follow a helical path and actu-ate -tumblens which changeover or break contacts, as a function `of the length of travel of the `operating mem- Iber.

The operating shaft can carry fout a number of revolutions, being coupled for example -to the cage of a lift by means of a suitable step-down gearing, so that the total length `of the helix described by the operating arms is in relation to the total height of displacement of the cage.

Selector apparatus of kind already known are heavy and bulky, and do not offer all the desired guaran tees with regard to rapidity and accuracy of operation ofthe contacts.

It should be observed that byA reason of the very considerable step-down ratio between the number of revolutions of the shaft of the switch and the travel ot the controlled apparatus, the helicoidal movement is very slow and sometimes even hesitant if there exists any considerable play in the mechanical transmissions.

However, the rocking movement of the contacts must be free, rapid and definite for the same direction of operation of the apparatus.

To this end, use may be made of rocker devices of the type Iwith a double rocking movemenn comprising two levers, one lof which is forked.

In the event of the device getting out `ot order, the forked lever may break. In order to avoid this happening, attempts have been made in prior constructions to provide this lever with a ilexible system, but this is complicated :and costly.

Furthermore, micro-switches are known which themselves comprise two pivoted levers lof unequal length and cou-pled `together by a U-shaped or omega-shaped spring, one of Ithese levers being actuated by 1an operating member and transmitting this `actuation to the other lever which carries a contact stud moving .between two fixed studs.

This transmission of the control is veiiected by means of two springs arranged symmetrically on each side of the first controlled lever and by means of the U-sh-aped spring.

In addition, yagain because of the inaccuracy lof transmission between the cont-rolled apparatus, for lexample in the cas-e of lifts, due to the elongation of 4the cables, the helicoidal travel of the shaft may become` out of adjustment with respect to the movement of the moving device.

In the prior apparatus, it has already been suggested to provide a substantial lost u'avel at each extremity of the travel of the' member in helicoidal movement, in order that the latter f cannot come into abutment against the iixed portions andV thus cause a breakage. It has also been proposed to construct this member in the form of a sleeve screwing on a screw rigidly iixed 'to the frame of the apparatus.

ice

The present invention relates to a switch of the screwselector type comprising in combination a driving sleeve having a bore which can slide ion a rotating shaft, and comprising a threaded portion screwing on a screw rigidly fixed to the frame of the apparatus, =a micro-switch with a snap-action blade iand return spring, and .a double acting rocker device Ifor open-ating the said micro-switch, absolutely independent of the latter, :and in which only a U-spring causes the abrupt movements of the microswitch. v

The rocker device comprises two levers of unequal lengths articulated like scissors and coupled together by the U-spring bearing on blades of these levens.

The lever of Smallest length rocks inside the lever of the longer length, which is operated directly by the actuating member. i A

A driving device with balls rigidly fixed to Ithe rotating shaft transmits the rotation of the said shaft.

The balls yot' the drivingv device nd their position in longitudinal grooves formed in the interior Iof the rotating sleeve.

The ball device operates also as .a de-clutching limiter, and to this end, the edges of the grooves are ilattened over about half their length, .and facing :a flattened portion of an edge is la non-flattened portion of the opposite edge ot the other groove.

The grooves lare formed in an intern-al liner of the rotating sleeve, the liner being made of plastic material to permit dry friction.

Other particular features and advantages of the present invention will become lapparent from the description which `follows below with reference to the accompanying drawings, in which:

FIG. l is a view vin cross-section or" a switch of the Screw selector type in 4accordance with the invention.

FIG. 2 is a view in longitudinal section of the sleeve with a helicoidal travel.

FIG. 3 is a diagram representing the grooves off the internal lining of the sleeve.

invention, in diiierent positions of oper-ation.

FIGS. 7. and 8 Show respectively in sectional elevation and in plan View, the forked lever of the rocker device. FIGS. 9 and 10 show also in sectional elevation and in plan view, the second lever of the rocker device.

Finally, FIGS. ll and l2. are views locking on the end and from above the spring overshooting the dead centre.

In the form of embodiment shown, the apparatus according to the invention comprises a shaft 1 driven in rotation by a pinion or 'gear 2 under the action of a contnolled moving body. At the end lof this rotating shaft and on the extension of its axis, is arranged a fixed screw 3 fast with a frame 4. Between the shaft 1 `and the xed screw 3, a rotating and sliding `sleeve 5 is provided on one end 6 of its bore with a nut 7 threaded on said screw 3, whereas the other portion 8 `of the bore, 1turned towards the shaft, receives the movement of this latter by a member 9 projecting yfrom .the said shaft, which may be `a lug or a key and `slides in lgrooves I10 and 10a of the sleeve (see FIG. l).

The member projecting -f-rorn the shaft is advantage- Atou-sly constituted by at least one set of two balls 11 and The liner 5al of moulded material comprises all the' working par-ts of the sleeve, namely the nut 7 `and the longitudinal grooves 10 .and 10a, permitting the drive the spring 26.

by the balls 11 and 11a of the projecting member 9 of the shaft. One of the edges of these grooves is flattened along a gradual slope 14 so as 'to calibrate the maximum (13 Votr 13a) llattened on the grooves '10i and 1Go is reversed towards the middle of the length of the said groove-s. In other Words, the edges are only flattened along'one half of their length and a atten'ed portion of an Vedge 13 of the groove 10, for example, faces a nonencounter during its travel at least one rocker device 17 lixedly mounted on the frame of the apparatus., Therocker device17 is of the double-acting type comprising the combination:

(a)L of a micro-switch 18 with a snap-action blade 18a, y

returned to one of its positions by an internal spring 19; (b) of ia mechanical rocker comprising two levers 20 and f21 mounted on the same shaft 22 which is in turn parallel toy the rotating shaft y1., The levers are provided 'with means (20a and Ztlbfor the lever 2l); 21a for the lever 21) constituting abutments which limit their'- travel, and each having a portion inthe form of `a' blade 23 against which is :applied the force of a dead-centre f overshoot spring 24.

The first lever Ztl isprovided at one extremity with a forked portion '25 mounted so as tobe driven, rocked and then left in its stable position by the helical rotation of the arm 16. This first lever is made in the :forni `of a frame through which the shaft 2.2` passes in the bores 22a and; containing 'the' smaller second lever 21, the whole lstress ofthe de-iclutching. The choiceiof one of the edges being arranged like a pair of scissors with arms ol' unequal v 'length (FIGS. 4 to 8).

In accordance with this arrangement, the small lever 21 is also traversed by the shaft Z2, passing through` a hole or bore 22a formed in this lever. The hole 22a of the lever 21 is of course in alignment with the holes 22a of the 4frame lof the lever 20;

The small lever Z1 is provided at the extremity opposite tothe spring 24 with la heel Z6 which transmits motion by contact with the push-rod l2,7 `of vthe micro-switch 18 (FIGS. 4 to 6` and 9 and 10).

, One or rbothof these levers may preferably be or light moulded material with high resistance to wear.

The dead-centre overshoot spring 24 is a spring blade curved in a U, with two lateral slots 29 on one arm 28,

while the other armf3tl` hasan axial hole 31, permitting 'immediate removal from between the levers (FIGS. `11

and 12).

y The arm 28 of the spring is in contact with the knifeedge 23 of the lever 20. f

'I'he arm 3l) of the spring is in contact with the knifeedge 23 ofthe lever 21. y

' The knife-edge 23 of the lever Ztl is provided at its eX- tremities with noses l3f?. which engage in the slots 29 of f i v the following manner:

it shouldbe observed that the two levers 2t) and 21 of the The driving device with balls 11 and `11a transmits the rotational movement `of the shaft `1 to the sleeve 5 in one Y direction or the other, by reason `ofthe housing of the balls 11'and 11a in the grooves 1i) and 10a of the sleeve. This ball driving device also acts 'as an effort limiter which automatically idisengages if the' sleeve comes at the end of its travel against the walls of the casingeither on the end 6 or on the end 8.

Itmaybe observed that, for one direction of rotation (f4 or f2, FIG. 3), thev effort of the vballs to `free them- `selves from the grooves of the blocked sleeve can only` be applied on the llattened edge 14 ofthe grooves. When the direction of fb. v

f The blade 18 then returns the contacts of the microtheoorrect adjustment is re-established, the sleeve S-Sa being -at this moment in the raised position, and resting on' the base by its abutment 2Gb. The arm 16 then drives the lever Ztl into the position shown in FIG. 4,the knife-edge 23 o f the lever 20, the knife-edge 23 of the lever 2.1and the rocking axis '22 being then located on the same straight line of dead centres. The spring 24 is compressed by oney of its arms.` When the arm 16 again turns through a very small angle, the limb Sil' of the springapplies on the lever 21 a force having a tangential component which is still very small, while the knife-edge 23 of the lever 21 is still subjected to a tangential force of opposite direction, due

, to the iorce of the spring 19 in the direction f1. The

abrupt rocking action of the lever 2,1V in the direction fzb will take place when thetangential component due to the limb Sil of the springwill have become large enough, and thus, for a certain angle of travel, after the passage of knife-edges 23 through theline ofdead centres. The system then rapidly takes the ,position shown in FIG; 5, the push-rod 27 being depressed in thedirection f3 andthe snap-blade la abruptly changes the position of the contacts of the micro-switch 18. When starting from the position shown in FIG. 5, and the arm :16 rotates in the direction f4 opposite to that preceding, it rfstdrives the leverZtl inthe clockwise direction up tothe position shown in FIG. 6, in which the knife edges 23 of the leversl 2l) and '21 and the centre of rotation 22 are almostin a straight line, the knife-edge of the lever 21 being still a little behind the line of dead centres.

The tangential component of the transverseforce due to the-limb 30 of the spning '24 is still directed in the'V beiore passing over the line ofdead-centres, the system rocks the lever Ztl in the direction ha and the lever Z1 in switch abruptly into their initial position.

In the two rocking movements, assuming the total stoppage of the arm 16 in the centre of the angle of travel of the lever 20, the system has `no possibility of remaining in equilibrium.

The main advantage of the rocker device accordingto the invention resides in that` the pressure on the electrical contacts of the microswitch 13, which is annulled at the moment when the contacts separate, cannot be vannulled slowly while the levers 2t) and 2-1 are in the vicinity of the position of equilibrium, for, at that moment, the push-rod 27 is still in one of its extreme positions (FIGS. 4 and 6);

rocker device 17 have a common shaft 2,2, which simplies the'construction.

Finally it is possible that due to mal-adjustment, the operating arms 16 engage the fork 25ct the lever 20 of the rocker device 17 in the wrong direction, that visto say when Vthe latter has already rocked over. v The limiter device for disengagement by balls -11 and 11a also plays its part in this case, and oifetrs without any addition the same protection against breaking of the forked lever Ztl. l

The construction of the yfrictional parts of plastic matey rial such as nylon gives the apparatus according to the invention Ia very long life, while at the same time it gives only a very small inertia to the moving parts.

I claim: 1. A screw type selector lfor the operation and control of a moving device having a to-and-fro movement cornprisng a frame, a ixed screw fast with said lErrnne, `a transmission coupled to the moving device,

a rotating shaft in said transmission, fa sleeve screwing on said xed screw and sliding on said rotating shaft, 4

arms mounted on said sleeve and adapted to follow a helical .path which is a function of the length ot `tha-vel of the moving device,

a double action rocker device in the path of said arms adapted to -be actuated by said arms,

two pivoted levers of unequal lengths in said rocker device, l

a micro-switch in operative relationship with said pivoted levers positioned to be actuated lby one of said llevers and having a snap-action blade,

and a U-spring `in said rocker device adapted when .actuated to cause, by its own actio-n, the abrupt displacement of said micro-switch.

2. The screw type selector of claim 1, further characterized by said levers being articulated as scissors and having and said U-spring being supported on said knife-edges of said levers. 3. The screw type selector of claim 2, Ifurther characterized by a push rod on said micro-switch in operative relationship with the shorter of said levers of unequal length,

the longer of said levers, of unequal length having two limbs thereon and in openative relationship with said arms,

the shorter of `said levers positioned between said limbs of said longer lever and adapted to rock therebetween.

4. The screw type selector of 'claim 1, Ifurther terized 'by said sleeve having longitudinal grooves,

characand al device 4with balls `coupled to said rotating shaft and in `driving relationship with said sleeve, said balls located in said longitudinal grooves of said sleeve. 5. The screw type selector of c1-aim 4, further characterized -by said levers being articulated as scissors and having knifeedges, andfsaid U-spring being supported on said knife-edges of said levers. 6. The screw type selector of claim 4, further characterized by the edges of said grooves -being flattened over about half of their length so that one attened portion of an edge faces a non-attened Iportion of the opposite edge of another groove and so that said device with 'balls is adapted to operate either as a drive for said grooved sleeve or as a de-clutching limiter device. 7. The screw type selector of claim 6, further characterized -by said 4lever-s being articulated as scissors and having knife-edges, and said U-spring Ibeing supported on said knife-edges of said levers.

8. The screw type selector of claim 1, lfurther characterized by an internal liner for said sleeve madeffrom a plastic material permitting dry friction and having longitudinal grooves therein, and a device with balls coupled to said rotating shaft and in driving relationship with said sleeve, said balls located in said longitudinal grooves of said sleeve. 9. The screw type selector of claim 8 further characterized by said levers being articulated as scissors and having knife-edges land said U-spring being supported on said knife-edges of said levers.

References Cited in the le of this patent UNITED STATES PATENTS Germany Oct. 3, 

1. A SCREW TYPE SELECTOR FOR THE OPERATION AND CONTROL OF A MOVING DEVICE HAVING A TO-AND-FRO MOVEMENT COMPRISING A FRAME, A FIXED SCREW FAST WITH SAID FRAME, A TRANSMISSION COUPLED TO THE MOVING DEVICE, A ROTATING SHAFT IN SAID TRANSMISSION, A SLEEVE SCREWING ON SAID FIXED SCREW AND SLIDING ON SAID ROTATING SHAFT, ARMS MOUNTED ON SAID SLEEVE AND ADAPTED TO FOLLOW A HELICAL PATH WHICH IS A FUNCTION OF THE LENGTH OF TRAVEL OF THE MOVING DEVICE, A DOUBLE ACTION ROCKER DEVICE IN THE PATH OF SAID ARMS ADAPTED TO BE ACTUATED BY SAID ARMS, TWO PIVOTED LEVERS OF UNEQUAL LENGTHS IN SAID ROCKER DEVICE, A MICRO-SWITCH IN OPERATIVE RELATIONSHIP WITH SAID PIVOTED LEVERS POSITIONED TO BE ACTUATED BY ONE OF SAID LEVERS AND HAVING A SNAP-ACTION BLADE, AND A U-SPRING IN SAID ROCKER DEVICE ADAPTED WHEN ACTUATED TO CAUSE, BY ITS OWN ACTION, THE ABRUPT DISPLACEMENT OF SAID MICRO-SWITCH. 